TinyOS Applications

transcript

TinyOSApplications

Advanced Computer Networks

TinyOS Applications Outline

AntiTheft Example– LEDs, timer, booting

Sensing Example– Light Sensor– Wiring to AntiTheft

Single Hop Networks– Active Messages interface– Sending packets– Receiving packets

Advanced Computer Networks TinyOS Applications 2

AntiTheft Example [List 6.1]

module AntiTheftC { uses { interface Boot; interface Timer <Tmilli> as WarningTimer;

interface Leds; }}

implementation { enum { WARN_INTERVAL = 4096, WARN_DURATION =

64 }; Advanced Computer Networks TinyOS Applications 3

can only declare integer constants

AntiTheft Example [List 6.1]event void WarningTimer.fired ( ) { if (call Leds.get ( ) & LEDS_LED0) { /* Red LED is on. Turn it off, will switch on

again in 4096 – 64 ms. */ call Leds.led0Off ( ); call WarningTimer.startOneShot (WARN_INTERVAL –

WARN_DURATION); } else { // Red LED is off. Turn it on for 64 ms. call Leds.led0On ( ); call WarningTimer.startOneShot (WARN_DURATION); }}

event void Boot.booted ( ) { /* We just booted. Perform first LED transition */ signal WarningTimer.fired ( ); }}interface Leds { [List 6.2]… async command void led0On ( ); async command void led0Off ( ); async command uint8_t get ( );}

AntiTheft Example [List 6.1]

software signal

AntiTheft configuration [List 6.6]

configuration AntiTheftAppC { }implementation { components AntiTheftC, MainC, LedsC; components new TimerMilliC ( ) as WTimer;

AntiTheftC.Boot -> MainC; AntiTheftC.Leds -> LedsC; AntiTheftC.WarningTimer -> WTimer;}

Sensing Example TinyOS provides two standard interfaces for reading sensor samples– Read :: acquire a single sample– ReadStream :: sample at a fixed rate.

interface Read <val_t> { command error_t read ( ); event void readDone (error_t, val_t val );

} Advanced Computer Networks TinyOS Applications 7

Sensing Example [List 6.8]

module DarkC { uses { interface Boot; interface Leds; interface Timer<TMilli> as TheftTimer;

interface Read<uint16_t> as Light; }}

implementation { enum { DARK_INTERVAL = 256, DARK_THRESHOLD = 200};

event void Boot.booted ( ) { call TheftTimer.startPeriodic (DARK_INTERVAL); } event void TheftTimer.fired ( ) { call Light.read ( ); //Initiate split-phase light

sampling }

/* Light sample completed. Check if it is a theft. */

event void Light.readDone (error_t ok,uint16_t val) {

if (ok == SUCCESS && val < DARK_THRESHOLD)

call Leds.led2On ( ); /* Alert! Alert! */ else call Leds.led2Off( ); /* Don’t leave LED on

Sensor Components Sensors are represented in TinyOS by generic components, e.g., PhotoC for the light sensor on the mts310 board.

generic configuration PhotoC ( ) { provides interface Read<uint16_t>;

}Advanced Computer Networks TinyOS Applications 11

AntiTheft Light Sensor Wiring [List 6.9]

configuration AntiTheftAppC { }implementation {… /* the wiring for the blinking Red LED */ components DarkC; components new TimerMilliC ( ) as TTimer; components new PhotoC ( );

DarkC.Boot -> MainC; DarkC.Leds -> LedsC; DarkC.TheftTimer -> TTimer; DarkC.Light -> PhotoC;}

Single Hop Networks TinyOS uses a layered network structure where each layer defines a header and footer layout.

The lowest exposed network layer in TinyOS is called active messages (AM).

AM is typically implemented directly over a mote’s radio providing unreliable, single hop packet transmission and reception.Advanced Computer Networks TinyOS Applications 13

Single Hop Networks Packets are identified by an AM type, an 8-bit packet type.

‘Active Messages’ indicates the type is used automatically to dispatch received packets to an appropriate handler.

Each packet holds a user-specified payload of up to TOSH_DATA_LENGTH bytes (normally 28 bytes)**.

A variable of type message_t holds a single AM packet.

** changeable at compile time. Advanced Computer Networks TinyOS Applications 14

Platform-Independent Types

TinyOS has traditionally used structs to define message formats and directly access messages.

Platform-independent structs are declared with nx_struct and every field of a platform-independent struct must be a platform-independent type.

nx_uint16_t val ; // A big-endian 16-bit valuenxle_uint32_t otherval; // A litte-endian 32-bit

TinyOS 2.0 CC2420 Header [List 3.32]

typedef nx_struct cc2420_header_t ** { nxle_uint8_t length; nxle_uint16_t fcf; nxle_uint8_t dsn; nxle_uint16_t destpan; nxle_uint16_t dest; nxle_uint16_t src; nxle_uint8_t type; } cc2420_header_t;The CC2420 expects all fields to be little-endian.

Theft Report PayloadPlatform-independent struct in the antitheft.h header file:

#ifndef ANTITHEFT_H#define ANTITHEFT_Htypedef nx_struct theft { nx_uint16_t who;} theft_t;…#endif

struct to define payload

AMSend Interface [List 6.12]

Contains all the commands needed to fill in and send packets:

interface AMSend { command error_t send (am_addr_t addr,

message_t* msg, uint8_t len); event void sendDone (message_t* msg, error_t

error); command error_t cancel (message_t* msg); command uint8_t maxPayLoadLength ( ); command void* getPayLoad (message_t* msg,

uint8_t len);}

Sending Report-Theft Packets [List 6.13]

uses interface AMSend as Theft;…message_t reportMsg;bool sending;void reportTheft ( ) { theft_t* payload = call Theft.getPayload (&reportMsg, sizeof (theft_t) ); if (payload && !sending) { //Payload fits and we are idle – Send packet payload->who = TOS_NODE_ID; //Report being stolen! //Broadcast the report packet to everyone if (call Theft.send(TOS_BCAST_ADDR, &reportMsg, sizeof (theft_t) ) == SUCCESS) }} Advanced Computer Networks TinyOS Applications 19

event void Theft.sendDone (message_t *msg, error_t error) { sending = FALSE; //Our send completed}

Sending Report-Theft Packets [List 6.13]

Generic AMSenderC configuration

generic configuration AMSenderC (am_id_t AMId) {

provides { interface AMSend; interface Packet; interface AMPacket; interface PacketAcknowledgements as Acks; }}

Communication StackCannot switch itself on and off on-demand, and needs the SplitControl interface to start and stop the radio:

interface SplitControl { [List 6.14]

command error_t start ( ); event void startDone (error_t error);

command error_t stop ( ); event void stopDone (error_t error);} Advanced Computer Networks TinyOS Applications 22

MovingC using SplitControluses interface SplitControl as CommControl;…event void Boot.booted ( ) { call CommControl.start ( ) ;}

event void CommControl.startDone (error_t ok) {

//Start checks once communication stack is ready

call TheftTimer.startPeriodic (ACCEL_INTERVAL);}

event void CommControl.stopDone (error_t ok) { }

Moving C Receiving Packet MovingC receives a packet payload (defined as a struct contained in a header file) that contains acceleration settings for detecting movement of the mote:

typedef nx_struct settings { nx_uint16_t accerVariance; nx_uint16_t accelInterval;} settings_t;

struct to define payload

AM Packet Reception Provided by the TinyOS Receive interface:

interface Receive { event message_t* receive(message_t* msg, void* payload, uint8_t len);}

Receive.receive, as a receive “handler”, receives a packet buffer which it can simply return or return as a different buffer if the handler wants to hold onto buffer.

MovingC Receiving Packet [List 6.16]

uses interface Receive as Setting;…uint16_t accelVariance = ACCEL_VARIANCE;

event message_t *Settings.receive (message_t *msg, void *payload, uint8_t len) { if (len >= sizeof (settings_t)) //Check for valid packet { /* Read settings by casting payload to settings_t,

reset check interval */ settings_t *settings = payload; accelVariance = setting->accelVariance; call TheftTimer.startPeriodic (setting->accelInterval); } return msg;}

TinyOS Applications Summary

AntiTheft Example– LEDs, Timer, Boot– get, enum

Sensing Example– Light Sensor– Read (split-phase)– Wiring to AntiTheft– Two Timer instances

TinyOS Applications Summary

Single Hop Networks– Active Messages, typed messages– Platform-independent types

Sending packets– AMSenderC generic configuration– SplitControl of Radio Stack– Structs for packet payloads

Receiving packets– Implemented as a receive event

handler.Advanced Computer Networks TinyOS Applications 28

TinyOS Applications

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